Pick random element from array, but unique

Question

I have array of countries. I want to pick 5 random countries from my array list, but I want them to be unique. This is what I have so far:

String allCountries[] = {"Finland", "Latvia", "Poland", "Afghanistan", "Albania", "Algeria"};

String country1 = (allCountries[new Random().nextInt(allCountries.length)]);
String country2 = (allCountries[new Random().nextInt(allCountries.length)]);
String country3 = (allCountries[new Random().nextInt(allCountries.length)]);
String country4 = (allCountries[new Random().nextInt(allCountries.length)]);
String country5 = (allCountries[new Random().nextInt(allCountries.length)]);

What is the best way to compare those strings while generating random elements?

Edit:

I expressed myself bad. The problem I have is that I don't want string country1, country 2 etc. to be same... so I want them to be always different.

Solution:

Collections.shuffle(Arrays.asList(allCountries));

You don't want them to be unique? If so why do you need to compare them, what you have should work fine. — Mark Peters
– Mark Peters, Commented Jul 18, 2011 at 12:38
Your title and question are conflicting. Do you or do you not want unique? — Perception
– Perception, Commented Jul 18, 2011 at 12:39
You don't or you do? Please clarify the contradicting title. — adarshr
– adarshr, Commented Jul 18, 2011 at 12:39
Sorry, I expressed myself bad... I will change the question. — Badr Hari
– Badr Hari, Commented Jul 18, 2011 at 12:40

alex · Accepted Answer · 2011-07-18 14:36:45Z

19

Shuffle the array and then slice the first 5 elements.

This will guarantee 5 unique random elements.

edited Jul 18, 2011 at 14:36

answered Jul 18, 2011 at 12:41

alex

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1 Comment

Badr Hari Over a year ago

Excellent idea... I also added the code to my question. Thank you :)

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